This invention relates to novel chlorosilane compounds having a thexyl group, and a process for preparing the same. These novel compounds are useful as a silylating agent because their bulky substituent group improves the stability of silylated products.
Silylating agents are used with alcohols and carboxylic acids for the purpose of protecting active hydrogen-bearing substituent groups thereon. The silylated compounds are useful in a variety of applications, typically as intermediates to pharmaceutical drugs and pesticides.
Most common among the silylating agents are compounds having a silicon-chlorine bond within their molecule, known as chlorosilane compounds. Silylation is effected by reacting the chlorosilane compounds with alcohols or carboxylic acids. The silylating agents of the chlorosilane type currently used in the art include trimethylchloro-silane, triethylchlorosilane, t-butyldimethylchlorosilane and triisopropylchlorosilane. However, products silylated with these silylating agents have insufficient steric bulkiness so that they are prone to hydrolysis and unsatisfactorily stable. There is a need for a silylating agent having a bulky substituent group to ensure that the product silylated therewith becomes more stable.
An object of the invention is to provide a chlorosilane compound having a bulky substituent group useful as a silylating agent capable of affording more stable silylated products. Another object is to provide a process for preparing the chlorosilane compound.
It has been found that a thexylchlorosilane compound having the following general formula (1): 
wherein each of R1 and R2 is a monovalent branched hydrocarbon group of 3 to 10 carbon atoms having a hydrocarbon group at the same or different xcex1- or xcex2-position or a monovalent cyclic hydrocarbon group of 3 to 10 carbon atoms can be prepared by reacting 2,3-dimethyl-2-butene with a hydrogenchlorosilane compound having the following general formula (2):
HSiR1R2Clxe2x80x83xe2x80x83(2)
wherein R1 and R2 are as defined above, in the presence of aluminum chloride. This chlorosilane compound having a thexyl group, simply referred to as thexylchlorosilane compound, is novel. When used as a silylating agent, it affords a more stable silylated product.
Accordingly, the invention provides a thexylchloro-silane compound of the formula (1). The invention also provides a process for preparing the thexylchlorosilane compound of the formula (1) by reacting 2,3-dimethyl-2-butene with a hydrogenchlorosilane compound of the formula (2) in the presence of aluminum chloride.